hard to start revisited

[IIv SHaDoW vII]

420a-1998 GS
I have been trying to diagnose this to no avail. I replaced the fuel pump because it was bad, the fuel filter, and did a full tune up and the car still is hard to start sometimes.
I did a tune up because it was needed, but I had hoped it would fix the problem.. Basically, the car will start fine sometimes, but other times it will take multiple tries to turn over, and lastly, sometimes it will start and die immediately.. Once started it runs and drives perfectly with no problems. It just has hard to start moments.. The only things left that have not been replaced that I can think could be causing this is maybe the Camshaft position sensor or fuel pressure regulator. There is no CEL on. By hard to start, I mean the car cranks but shows the symptoms listed above..

 

[Friend-O]

any fuel system upgrade, a missing or bad fuel pressure reg. or dirty injectors/ old plugs can be the culprit. My fresh engine build, on a could start i have to kick it over twice to get the fuel lines primed enough to get it kicked over. After warm up it starts right up successively on the first try. Im not sure if the 420a has them but there should be a vac line from the fuel press. regulator going to a solenoid and then to a vac. port. That solenoid aids in cold starts and un-primed starts.

 

[rstare]

Trying using some fuel injector cleaner. Or, pull the fuel injectors and send them to have them cleaned. The fuel pressure should be ~53psi, so check that and make sure it's right.

 

[gudz519]

in all honesty i would try simple things i had this problem it ended up being a faulty temperature sending unit and a vacuum leak check those things out

 

[IIv SHaDoW vII]

Thanks for the replies.. I bought some fuel injector cleaner today and plan to use it on next fill-up. I have searched for vacuum leaks but I will attempt to check again. The temperature sending unit was replaced last year but I will swap it with the old one for a bit to see if the hard starts go away.

 

[IIv SHaDoW vII]

Well, I tried the above tests. I used some telcron fuel system cleaner, checked again for vacuum leaks, made sure my new spark plugs were torqued to specs, checked fuel system for leaks in the hoses, and ran a check on the engine codes just to make sure there were no stored codes. The CEL diag returned a P0401 insufficient EGR flow but this has been on for years due to the previous owner removing the vacuum hose from the intake to the EGR and capping both ends. I am not sure why he did it but I never bothered fixing it. Anyway, the only thing left for me to do that I can think of is test the fuel pressure regulator.
Are there any engine sensors that could cause this problem that would potentially NOT throw a CEL?
Any other thoughts?

EDIT: After doing a bit of searching on other forums, I see people saying that it could be the ignition switch or fuel pump relay. I was always told that fuel pump relays are either working or not.. In my case, I assume since the car starts fine most of the time, it shouldn't be the relay.. However, the ignition switch has me puzzled. Do you guys think this could be the problem? Anyone ever have this problem before?

 

[rstare]

Try checking the temperature sensors.

 

[csquier74]

EDIT: After doing a bit of searching on other forums, I see people saying that it could be the ignition switch or fuel pump relay. I was always told that fuel pump relays are either working or not.. In my case, I assume since the car starts fine most of the time, it shouldn't be the relay.. However, the ignition switch has me puzzled. Do you guys think this could be the problem? Anyone ever have this problem before?

It is possible for a relay to be sticky, so don't rule out the fuel pump relay completely. If you have someone to help you, have them even just touch the relay when you turn on the ignition, and they should be able to feel it click. Definitely check your fuel pressure at the rail. Very possible that it's a fuel pressure regulator problem.

 

[bullettdsm]

I'm wondering about a bad connection/bad sensor on the CPS. Maybe just enough to cause a problem but not cause a cel Possibly the connector clip is broken or worn and the connection slips. Or maybe there is a wire along the EGR tube that is burnt up.

Just thinking outside the "norm".

MB

 

[IIv SHaDoW vII]

An update on the problem. I swapped both temp sensors with known working ones and the problem still remains.

I am beginning to believe it is a fuel problem as well.. I have been doing a simple test lately where I don't try to start it until it has finished priming the lines. So far this test has been successful (as in, the car starts every time) which makes me think its something fuel related. There are no leaks in the fuel lines, the pump is new, and the filter is new. I hear the buzz every time I start the car so I assume my relay is still good. I will check it out though. This leaves the fuel pressure regulator.. If this were going out.. it would probably cause similar symptoms to what I am observing, correct?

 

[IIv SHaDoW vII]

Alright, my problem is definitely fuel related. Ever since I started to let it prime first, it starts right up. My question is, what could cause such an emergent problem like this? What are the symptoms of a bad FPR? My first guess with me needing to allow it to prime completely before starting every time would be that I am losing pressure somewhere. I know I have no leaks on the lines, nor around the fuel filter. Also, forgive me for not regarding this sooner.. I saw someone tell me to check the psi at the rail.. Is there any other stuff I should try first?

 

[96TurboGS]

I would rent a fuel pressure tester before proceeding just to make sure you're getting the fuel pressure you need from your fuel system. I would test at start up and in running mode. A lack of fuel pressure normally causes the problem your seeing, assuming your spark plugs are gaped properly/good condition and the coil and wires are within spec. The IAT and CLT circuits are also critical as there could be added resistance in the circuit somewhere. (Only way to find out is the use of a logger or taking it to a shop with something like a snap-on scanner. EDIT: or if you measured the resistance from the PCM to the sensor without the sensors/PCM connected.)

 

[csquier74]

shadow,

I had the very same problem. In my case, it ended up being the fuel pump. I replaced the injectors and FPR to no avail. Fuel pump fixed immediately. I replaced the stock fuel pump with a walbro 255lph hp for $90 shipped. Cheaper than an OEM replacement from a parts house...

 

[IIv SHaDoW vII]

Thanks for the reply, but my fuel pump is brand new and I rechecked the assembly twice for problems that may have caused it to lose pressure. I'm wondering if I purchased a bad fuel pump..

 

[csquier74]

Any news on your problem?

 

[nothingfiction]

shadow,

I had the very same problem. In my case, it ended up being the fuel pump. I replaced the injectors and FPR to no avail. Fuel pump fixed immediately. I replaced the stock fuel pump with a walbro 255lph hp for $90 shipped. Cheaper than an OEM replacement from a parts house...

So you can run a 255 in the non turbo? i thought you should only get the 190 in NT and the 255 after turbo?

 

[IIv SHaDoW vII]

Thanks for the concern Csquier. The only update is, the car will start 100% of the time if I pressurize it first (wait for fuel pump buzz). It will randomly not start on the first try if I don't allow it to pressurize first. The fuel relay was swapped with another working relay and no change after driving for 2 weeks. I don't have access to a pressure tester to test the pressure of the fuel system.. Is there somewhere I can get one from?